Unless it's already here and I was completely oblivious, you should make a post like that and get it stickied or something, VERY informative and helpful and would prevent more modding questions in the future... or at the very least I could find it easier when I start implementing my own stuff

But you can export your model in Maya and then import it in Blender. Then make sure it's all triangles and you've got a UV mapping. Then export to .solid and replace a mesh.
Also works the other way around (import .solid in Blender, export from Blender, import in Maya).

As for animations, they're a custom job through and through.

If you want to write Maya plugins, that's cool. The python stuff from me is opensource, so it should be easy to copy if you know what you're doing.

So I had issues with the hoster for my scripts. And I've been asked where my scripts have gone. So since this seems to have become the modding resource thread, I've attached the scripts zipped to this post.